The technology for freezing shaft sinking is widely used for shafts to pass through deep, unstable alluvia with the continuous exploitation of mineral resources. Due to the technique using the sectional excavation and shaft lining construction adopted in deep alluvia, the radial stress at the inner edge of a frozen wall is incompletely unloaded. In this paper, a mechanical model was established for a frozen wall with its inner edge radially incompletely unloaded. A parameter, α, expressing the degree of being unloaded was introduced, and then a new method of designing and calculating the thickness of the frozen wall was proposed. The range of parameter α was estimated based on the frozen wall–shaft lining interaction forces from field data from a given project. The results indicate that the range of α can be chosen to be from 0.05 to 0.15 in deep alluvia. The design thickness of the frozen wall can be reduced by at least 5% for the frozen wall with the inner edge radially incompletely unloaded. The design thickness is significantly influenced by the strength and elastic modulus of the frozen soil and the elastic modulus of the surrounding unfrozen alluvium. The design and calculation method of frozen wall thickness can provide new ideas for guiding the design of frozen walls in deep alluvia.

Study of the compressive strength and damage constitutive model of frozen sand has an important significance for construction design and prevention-control of soil destabilization damage in frozen soil engineering. In this paper, a new triaxial apparatus was used to carry out a series of triaxial compression tests of frozen sand under different confining pressure and strain rate, based on which a segmental strength criterion is established to describe the damage of microelement strength of frozen sand. Assuming that the microelement strength of frozen sand obeys the Weibull distribution, a statistical damage constitutive model of frozen sand is established by statistics and continuous medium mechanics. Based on the test data, the model parameters were calculated and the relationship between the strength distribution parameters, the strain rate, and the confining pressure was obtained. Finally, the calculated values of the damage constitutive model are compared with the experimental values, and it is found that the model can simulate the stress-strain process curve of frozen sand well and can reflect the transition of the curve from elasto-plasticity to strain-hardening when the strain rate increases from low to high. The results of this study have an important significance in engineering construction of cold regions and artificial ground freezing projects.

As coal resource development progresses deeper underground, the increasing depth of mine shafts poses significant challenges to the safety and stability of traditional shaft construction methods, further compounding operational difficulties. In this context, cast-in-situ concrete shaft walls in a slurry environment have emerged as an effective solution. The strength of these shaft walls is a crucial parameter for assessing their safety. To explore this, experiments were conducted on slurry preparation and mortar casting (used here as a substitute for concrete) under three different conditions: slurry environment, pure water environment, and dry environment. The cast specimens underwent compressive, tensile, shear, and microscopic observation tests to analyze the strength development patterns of the mortar specimens in these varied casting environments. The study yielded several key findings: As the casting environment becomes more complex, the strength of the mortar specimens gradually decreases. Specifically, specimens cast in a slurry environment exhibit strengths approximately 15% to 20% lower than those cast in a dry environment, although both environments show similar trends in strength development over time. Across all casting environments, the initial strength loss of the specimens is significant, while the rate of strength loss decreases in the later stages; the strength loss is minimal in specimens cast in a pure water environment and reaches its maximum in those cast in a slurry environment. Additionally, in specimens cast in a slurry environment, air void diameter tends to polarize, and the distribution of air void is denser compared to the other two environments. In conclusion, cast-in-situ mortar in a slurry environment exhibits the lowest strength and the greatest strength loss compared to specimens cast in dry and pure water environments. Nonetheless, the strength development trends over time remain similar across all conditions, providing theoretical and technical support for the construction of shaft walls in slurry environments.

The mechanical properties of high-pressure frozen ice are critical design parameters for deep artificial ground freezing and ice sheet drilling operations, making their investigation fundamentally significant. In this study, ice specimens were prepared at −10 °C under freezing pressures of 10, 20, 30, 40, and 50 MPa. In situ axial loading simulation experiments were conducted to investigate their mechanical behavior and macroscopic deformation characteristics during failure. The experimental results indicate that the deviatoric stress–axial strain curves of the ice specimens exhibited a rapid yet smooth transition before and after reaching the peak deviatoric stress, with all samples exhibiting ductile failure. The peak deviatoric stress initially increased and then decreased with increasing freezing pressure, reaching a maximum value of 8.61 MPa at a critical transition pressure of 20 MPa, eventually declining to a minimum of 1.66 MPa at 50 MPa. The residual deviatoric stress decreased significantly with increasing freezing pressure, declining from approximately 3.5 MPa at 10 MPa to 0.85 MPa at 50 MPa. The peak tangent modulus demonstrated a fluctuating trend with increasing freezing pressure, ranging from 1.76 to 2.37 GPa. As the freezing pressure increased, the failed ice specimens transitioned from a densely cross-cracked state to a highly transparent phase, and finally to a sparsely cross-cracked morphology.

The inclined shaft lining cross-section is prone to severe issues such as shaft lining cracking and even structural failure due to geometric irregularity and mechanical complexity, posing significant engineering safety hazards. To address these safety concerns, this study introduces Optical Frequency Domain Reflectometry (OFDR) as a novel monitoring approach for inclined shaft linings. OFDR was implemented to measure strain distributions across both the inner and outer surfaces of a model shaft lining, with validation through comparative analysis against strain gauge measurements and numerical simulations. The findings indicate that: (1) OFDR provides accurate strain measurements consistent with conventional methods, and (2) has the ability to detect cracks that cannot be identified by the human eye. This study preliminarily achieved full-section monitoring of strain distribution on both the inner and outer edges of inclined shaft lining using OFDR technology, which holds significant implications for underground construction projects.

Shaft sinking in soft, water-rich strata frequently suffers from low cutting efficiency, cycle-time mismatches between excavation and muck removal, and weak system-level coordination. To elucidate the synergistic mechanisms governing excavation–muck removal interactions and to realize end-to-end performance gains, we investigate the East Ventilation Shaft of the Xinjie Taigemiao mining district as a representative artificial ground freezing (AGF) project. First, drawing on the mechanics of frozen ground and field monitoring, we establish a relationship model linking advance rate, drum rotational speed, cutting depth, and muck production, thereby clarifying why lower rotational speeds, moderate cutting depths, and rational traction reduce energy consumption and mitigate disturbances to the frozen wall. Next, for muck handling, we build a full-process discrete element method (DEM) model, integrate design-of-experiments with response-surface optimization to identify key factors, calibrate contact models, and select collection geometries. The results show that a graded-angle collecting structure improves pile concentration and discharge compliance; combined with a tiered chain-bucket–vertical belt–twin-skip configuration, it delivers matched cycle times and stable “gather–convey–hoist” operation. Finally, two-stage full-scale tests jointly validate excavation and muck removal, demonstrating that the proposed synergy model and optimized parameters sustain continuous, efficient performance across operating conditions. The study provides a reusable mechanistic framework and parameterization blueprint for AGF shaft design and construction.